Question: My mother loves touring and sightseeing, and she wants to go see the Acropolis in Athens. Given that many people believed in mythological gods at the time the Acropolis was built, is there a problem going there or not?
Answer: It’s doubtful that people believe in Greek mythology anymore, and highly doubtful that people are actively worshipping Greek gods there. Bittul — nullification — has the effect of ‘cancelling’ idolatry so that certain limited uses then become permissible. One can assume that there are people who over the years have treated this sight with disrespect*, which is automatically a bittul. Furthermore, the fact that the Acropolis is a ruin which is not being rebuilt constitutes a bittul of the idolatry. If your mother wants to go and see the Acropolis then she may do so. But as long as she’s going to Greece — have her hop on over to Israel for a visit!
* The writer of this ‘Ask the Rabbi’ once played Frisbee on the Acropolis grounds. Shhh!